Nickel cobalt lithium manganese cathode material, preparation method thereof and lithium ion battery

ABSTRACT

The disclosure discloses a nickel cobalt lithium manganate cathode material, a preparation method thereof and a lithium ion battery. The nickel cobalt lithium manganate includes a core and an outer layer covering the outside of the core, the core comprises flaky particles, a D50 particle diameter of the flaky particles in the core is 5-10 μm, and a D50 particle diameter of particles in the outer layer is 0.1-4.5 μm.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 16/650,835, filed Mar. 25, 2020, which is a national phaseentry under 35 U.S.C. § 371 of International Application No.PCT/CN2018/107934, filed on Sep. 27, 2018, which claims a priority toand benefits of Chinese Patent Application Serial No. 201710896969.5,filed on Sep. 28, 2017, the entire content of all of which isincorporated herein by reference.

FIELD

The disclosure relates to the field of a lithium ion battery and, inparticular, to a nickel cobalt lithium manganate cathode material, apreparation method thereof and a lithium ion battery.

BACKGROUND

An existing method for preparing the nickel cobalt manganese hydroxide,the nickel cobalt lithium manganate cathode material and a lithium ionbattery comprises the following steps of: (1) mixing sulfatesrespectively comprising nickel, cobalt and manganese together to bedissolved into deionized water to form a sulfate water solution A; (2)dissolving sodium hydroxide powder into the deionized water to form awater solution B; (3) diluting ammonium hydroxide with the masspercentage being 25-28% to a certain concentration to obtain a dilutedammonium hydroxide solution C; (4) simultaneously dripping the watersolution A in the step (1), the water solution B in the step (2) and theammonium hydroxide solution C in the step (3) into a reaction kettleunder the conditions of being protected by nitrogen gas, being stirredand being heated to 40-70° C., and after the reaction for a certaintime, performing washing and drying to obtain nickel cobalt manganesehydroxide precursor powder; (5) weighing and taking, and uniformlymixing a lithium source compound and the nickel cobalt manganesehydroxide precursor material in the step (4), heating the materials to600-1100° C. in air or oxygen gas atmosphere, performing continuouscalcination for 8-20 h at 600-1100° C., and then cooling the materialsto a room temperature to obtain a nickel cobalt lithium manganatefinished product material; (6) making the nickel cobalt lithiummanganate material obtained in the step (5) into a battery, but thelithium ion battery prepared from the prepared nickel cobalt manganesehydroxide and the nickel cobalt lithium manganate cathode material haspoor rate capability and poor high-temperature storage performance ofthe battery.

Therefore, we are in need of the nickel cobalt manganese hydroxide andthe nickel cobalt lithium manganate cathode material capable ofobviously improving the rate capability and the high-temperature storageperformance of the battery now.

SUMMARY

The disclosure aims at solving the problem of poor rate capability of alithium ion battery in the prior art, and provides a nickel cobaltmanganese hydroxide, a cathode material, a preparation method thereofand a lithium ion battery. The lithium ion battery prepared from thecathode material of the disclosure has high battery energy density andgood battery rate capability.

In order to achieve the above goal, the disclosure provides the nickelcobalt manganese hydroxide in a first aspect. The nickel cobaltmanganese hydroxide comprises a core and an outer layer covering theoutside of the core, wherein the core comprises flaky particles, the D₅₀particle diameter of the flaky particles in the core is 5-8 μm, and theD₅₀ particle diameter of particles in the outer layer is 0.1-5 μm.

The disclosure provides a method for preparing the nickel cobaltmanganese hydroxide in a second aspect. The method comprises thefollowing steps of mixing a water solution A comprising water-solublenickel, cobalt and manganese ions with a water solution B comprisingstrong base, and ammonium hydroxide in inert atmosphere to take acomplex-precipitation reaction, and then adding Ag powder to take apulse current coprecipitation reaction.

The disclosure provides a nickel cobalt lithium manganate cathodematerial in a third aspect. The nickel cobalt lithium manganate isprepared by calcining a lithium source and the nickel cobalt manganesehydroxide or the nickel cobalt manganese hydroxide prepared by theabove-mentioned method.

The disclosure provides a nickel cobalt lithium manganate cathodematerial in a fourth aspect. The nickel cobalt lithium manganatecomprises a core and an outer layer covering the outside of the core,wherein the core comprises flaky particles, the D₅₀ particle diameter ofthe flaky particles in the core is 5-10 μm, and the D₅₀ particlediameter of particles in the outer layer is 0.1-4.5 μm.

The disclosure provides a method for preparing a cathode material in afifth aspect. The method comprises the step of calcining the lithiumsource and the nickel cobalt manganese hydroxide or the nickel cobaltmanganese hydroxide prepared by the above-mentioned method.

The disclosure provides a lithium ion battery in a sixth aspect, and thelithium ion battery comprises the cathode material or the cathodematerial prepared by the above-mentioned method.

Primary particles of the nickel cobalt manganese hydroxide prepared bythe existing method are in compact distribution, so that thesubsequently prepared nickel cobalt lithium manganate finished productmaterial has poor rate capability although it has high energy density.In the disclosure, Ag powder is used as a conductive inducer, and aloose and porous nickel cobalt manganese hydroxide particle layer isformed on the existing compact nickel cobalt manganese hydroxideparticle surfaces in a pulse current coprecipitation mode. The nickelcobalt manganese hydroxide particles prepared by this method have thecompact inside and the loose and porous outside. Then the lithium sourceand the nickel cobalt manganese hydroxide are calcined, and are nextcooled to the room temperature to obtain the nickel cobalt lithiummanganate finished product material with the compact inside and theloose and porous outside. The specific surface area of the nickel cobaltlithium manganate finished product material is 0.1-10 m²/g, the D₅₀particle diameter of the inside compact secondary particles (core flakyparticles) is 5-10 and the D₅₀ particle diameter of outside looseparticles (outer layer particles) is 0.1-4.5 The lithium ion batteryprepared from the nickel cobalt lithium manganate finished productmaterial as the cathode material simultaneously has excellent batteryenergy density and rate capability.

Other aspects and advantages of the present disclosure will be given inthe following description, some of which will become apparent from thefollowing description or may be learned from practices of the presentdisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are provided to further understand the presentdisclosure, and they constitute a part of the application. Theaccompanying drawings, along with the detailed description below, areused to explain the present disclosure, and pose no limitation on thepresent disclosure.

FIG. 1 is an SEM (scanning electron microscope) pattern (30000 times) ofa nickel cobalt manganese hydroxide prepared according to an embodiment1 of the disclosure;

FIG. 2 is an SEM pattern (1000 times) of the nickel cobalt manganesehydroxide prepared according to the embodiment 1 of the disclosure;

FIG. 3 is an SEM pattern (20000 times) of a nickel cobalt manganesehydroxide prepared according to a contrast embodiment 1 of thedisclosure; and

FIG. 4 is an SEM pattern (1000 times) of the nickel cobalt manganesehydroxide prepared according to the contrast embodiment 1 of thedisclosure.

DETAILED DESCRIPTION

The following describes embodiments of the present disclosure in detail.Examples of the embodiments are shown in the accompanying drawings, andsame or similar reference signs in all the accompanying drawingsindicate same or similar components or components having same or similarfunctions. The embodiments described below with reference to theaccompanying drawings are exemplary, and are intended to explain thepresent disclosure and cannot be construed as a limitation to thepresent disclosure.

In the description of the present disclosure, it should be understoodthat orientation or position relationships indicated by the terms suchas “center”, “vertical”, “horizontal”, “length”, “width”, “thickness”,“above”, “below”, “front”, “rear”, “left”, “right”, “vertical”,“horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”,“counterclockwise”, “axial”, “radial”, and “circumferential” are basedon orientation or position relationships shown in the accompanyingdrawings, and are used only for ease and brevity of illustration anddescription, rather than indicating or implying that the mentionedapparatus or component must have a particular orientation or must beconstructed and operated in a particular orientation. Therefore, suchterms should not be construed as limiting of the present disclosure.

In addition, terms “first” and “second” are only used to describe theobjective and cannot be understood as indicating or implying relativeimportance or implying a quantity of the indicated technical features.Therefore, features defining “first” and “second” can explicitly orimplicitly include at least one of the features. In the descriptions ofthe present disclosure, unless explicitly specified, “multiple” means atleast two, for example, two or three.

In the present disclosure, unless otherwise explicitly specified ordefined, the first feature being located “above” or “below” the secondfeature may be the first feature being in a direct contact with thesecond feature, or the first feature being in an indirect contact withthe second feature through an intermediary. In addition, the firstfeature being located “above” the second feature may be the firstfeature being located directly above or obliquely above the secondfeature, or may simply indicate that the first feature is higher inlevel than the second feature. The first feature being located “below”the second feature may be the first feature being located directly belowor obliquely below the second feature, or may simply indicate that thefirst feature is lower in level than the second feature.

The endpoints and any values of the ranges disclosed herein are notlimited to the precise range or value, and these ranges or values shouldbe understood to include values close to these ranges or values. Anumerical range between endpoint values of each range, a numerical rangebetween an endpoint value and an individual point value of each range,and a numerical range between individual point values may be combinedwith each other to obtain one or more new numerical ranges, and suchnumerical ranges should be considered to be specifically disclosedherein.

The disclosure provides a nickel cobalt manganese hydroxide in a firstaspect. The nickel cobalt manganese hydroxide comprises a core and anouter layer covering the outside of the core, wherein the core comprisesflaky particles, the D₅₀ particle diameter of the flaky particles in thecore is 5-8 μm, and the D₅₀ particle diameter of particles in the outerlayer is 0.1-5 μm. It should be noted that the covering structure of thenickel cobalt manganese hydroxide is not a structure completely coveringthe core by the outer layer, and is a structure that small particles ofthe outer layer are attached onto the surfaces of flaky big particles ofthe core, gaps are loosely formed between the small particles of theouter layer, and a loose and porous outer layer is formed.

According to the nickel cobalt manganese hydroxide of the disclosure,the porosity of the core is 30-51%, and the porosity of the outer layeris 52-60%. Namely, the particles of the nickel cobalt manganesehydroxide of the disclosure have a compact inside and a loose and porousoutside. Then a lithium source and the nickel cobalt manganese hydroxideare calcined, and are next cooled to the room temperature to obtain anickel cobalt lithium manganate finished product material with thecompact inside and the loose and porous outside.

In the disclosure, the core porosity refers to the porosity by using thetotal volume of the core as the reference, and the outer layer porosityrefers to the porosity by using the total volume of the outer layer asthe reference.

The nickel cobalt manganese hydroxide of the disclosure preferably has achemical formula of Ni_(x)Co_(y)Mn_(1-x-y)(OH)₂, wherein 0<x<1, 0<y<1,and 0<1-x-y<1, so that the rate capability of the lithium ion batteryprepared from the nickel cobalt lithium manganate cathode material canbe obviously improved.

For the nickel cobalt manganese hydroxide of the disclosure, preferably,the D₅₀ particle diameter of the flaky particles in the core is 5-7.5μm, and the D₅₀ particle diameter of the particles in the outer layer is0.1-4.5 so that the rate capability of the lithium ion battery preparedfrom the nickel cobalt lithium manganate cathode material can beobviously improved.

The nickel cobalt manganese hydroxide of the disclosure preferablycomprises Ag, and preferably, the content of the Ag in the nickel cobaltmanganese hydroxide is lower than 20 ppm (preferably lower than 10 ppm),so that the influence on the subsequent performance of the lithium ionbattery by too high Ag content can be avoided. It should be noted thatthe existence form of the Ag in the nickel cobalt manganese hydroxide isnot specially limited, and the Ag can exist in a simple substance form,and can also exist in a compound form.

The nickel cobalt manganese hydroxide of the disclosure preferably hasthe specific surface area of 0.1-10 m²/g, more preferably 5-8 m²/g, sothat the rate capability of the finally prepared lithium ion battery canbe excellent.

The disclosure provides a method for preparing nickel cobalt manganesehydroxide in a second aspect. The method comprisoffing: mixing a watersolution A comprising water-soluble nickel, cobalt and manganese ions awater solution B comprising strong base, and ammonium in inertatmosphere to make a complex-precipitation reaction, and then adding Agpowder in it to make a pulse current coprecipitation reaction.

In the disclosure, the pulse current coprecipitation reaction refers toa coprecipitation reaction performed under the condition of pulsecurrent.

According to the method of the disclosure, a method for preparing thewater solution A comprising water-soluble nickel, cobalt and manganeseions can comprise the step of dissolving water-soluble nickel salts,water-soluble cobalt salts and water-soluble manganese salts into water.In the disclosure, the water-soluble nickel salts can be various kindsof water-soluble nickel salts in the art, such as at least one kind ofnickel salts from nickel sulfate, nickel nitrate and nickel chloride,preferably nickel sulfate. The water-soluble cobalt salts can be variouswater-soluble cobalt salts in the art, such as at least one kind ofcobalt salts from cobalt sulfate, cobalt nitrate and cobalt chloride,preferably cobalt sulfate. The water-soluble manganese salts can bevarious water-soluble manganese salts in the art, such as at least onekind of manganese salts from manganese sulfate, manganese nitrate andmanganese chloride, preferably manganese sulfate.

According to the method of the disclosure, preferably, the mol ratio ofelement Ni:Co:Mn in the water solution A is x:y:(1-x-y), wherein 0<x<1,0<y<1, and 0<1-x-y<1, so that the chemical formula of the preparednickel cobalt manganese hydroxide is Ni_(x)Co_(y)Mn_(1-x-y)(OH)₂,wherein 0<x<1, 0<y<1, 0<1-x-y<1, and the rate capability of the lithiumion battery prepared from the nickel cobalt lithium manganate cathodematerial is obviously improved.

According to the method of the disclosure, the concentration of thewater-soluble nickel, cobalt and manganese ions in the water solution Ais 0.1-3 mol/L, and preferably 0.1-2 mol/L. Herein, the concentration ofthe water-soluble nickel, cobalt and manganese ions refers to the totalconcentration of three kinds of elements of nickel, cobalt and manganesein the salt.

According to the method of the disclosure, the concentration of ammoniumhydroxide can be 0.1-1.6 mol/L, preferably 0.1-1.2 mol/L. The ammoniumhydroxide with the required concentration of the disclosure can beobtained by diluting ammonium hydroxide with the concentration being25-28%.

According to the method of the disclosure, the strong base can bevarious kinds of strong base in the art, such as sodium hydroxide and/orpotassium hydroxide. In the disclosure, the concentration of the strongbase in the water solution B can be 0.1-16 mol/L, preferably 0.1-10mol/L.

The strong base of the disclosure is a precipitating agent of thecomplex-precipitation reaction, and the ammonium hydroxide is acomplexing agent of the complex-precipitation reaction. Therefore, theconsumption of the strong base and the ammonium hydroxide in thedisclosure only needs to enable the full complex-precipitation of thenickel ions, cobalt ions and manganese ions in the water solution A toform nickel cobalt manganese hydroxide, and namely, the consumption ofthe strong base and the ammonium hydroxide only needs to be excessiverelative to the water-soluble nickel cobalt manganese salts.

The method of the disclosure preferably comprises the step of preparinga nickel, cobalt and manganese sulfate solution (water solution A) fromCoSO₄·7H₂O, NiSO₄·6H₂O and MnSO₄·H₂O, wherein in order to enable thecobalt, nickel and manganese ions in the solution to form the nickelcobalt manganese hydroxide, relative to 40 L of nickel, cobalt andmanganese sulfate solution with the concentration of 0.1-2 mol/L, theconsumption of the ammonium hydroxide with the concentration of 0.1-1.2molL⁻¹ is 0.1-40 L, and the consumption of the NaOH water solution(water solution B) with the concentration of 0.1-10 molL⁻¹ is 0.1-40 L.

In order to more uniformly prepare the nickel cobalt manganesehydroxide, the method of the disclosure preferably comprises the step ofsimultaneously dripping the water solution A, the ammonium hydroxide andthe water solution B into a reaction vessel under the stirringcondition, wherein the dripping speed can be 0.2-2 L/h, and the stirringspeed can be 4-10 ms⁻¹.

According to the method of the disclosure, the conditions of thecomplex-precipitation reaction can be various complex-precipitationreaction conditions in the art, for example, the conditions may comprisethe temperature being 40-70° C., preferably 40-60° C., and the timebeing 0.1-80 h, preferably 0.1-60 h (more preferably 0.1-20 h), so thatthe whole particle diameter distribution of the nickel cobalt manganesehydroxide can be controlled.

According to the method of the disclosure, a mode for taking the pulsecurrent coprecipitation reaction comprises the steps of inserting ametal electrode into the reaction vessel, forming an electrolytic tankbetween the metal electrode and the metal reaction vessel, then addingAg powder into the reaction vessel, and next introducing a pulse powersupply, wherein the metal electrode can be at least one kind ofelectrodes from a Pt electrode, an Au electrode and an Ag electrode,preferably the Pt electrode, and the reaction vessel can be variousconventional reaction vessels in the art.

According to the method of the disclosure, preferably, the conditions ofthe pulse current coprecipitation reaction comprise the pulse ratiobeing 1:(1-10), more preferably 1:(1-5), and the reaction time being0.1-40 h, more preferably 0.1-30 h, so that the porosity, the particlediameter distribution and the like of the core and the outer layer ofthe prepared nickel cobalt manganese hydroxide can be furthercontrolled, and the rate capability of the lithium ion battery preparedfrom the nickel cobalt lithium manganate cathode material can beobviously improved. In the disclosure, a pulse power supply being 0-32 Vcan be used for providing the preferable pulse ratio.

According to the method of the disclosure, relative to 1566 g of elementNi, the consumption of Ag powder is preferably 0.36-1 g, more preferably0.36-0.6 g, the porosity, the particle diameter distribution and thelike of the core and the outer layer of the prepared nickel cobaltmanganese hydroxide can be further controlled, and the rate capabilityof the lithium ion battery prepared from the nickel cobalt lithiummanganate cathode material can be obviously improved.

The method of the disclosure can also comprise the steps of washing anddrying slurry obtained through the pulse current coprecipitationreaction and obtaining the nickel cobalt manganese hydroxide, whereinthe washing times can be 3-7 times, and the drying temperature can be100-120° C.

In the disclosure, inert atmosphere can be provided by nitrogen gasand/or inert gas, wherein the inert gas can be He, Ne, Ar, Kr or Xe.

The disclosure provides a nickel cobalt lithium manganate cathodematerial in a third aspect. The nickel cobalt lithium manganate isprepared by calcining the lithium source and the nickel cobalt manganesehydroxide or the nickel cobalt manganese hydroxide prepared by theabove-mentioned method.

The disclosure provides a nickel cobalt lithium manganate cathodematerial in a fourth aspect. The nickel cobalt lithium manganate in thenickel cobalt lithium manganate cathode material comprises a core and anouter layer covering the outside of the inner core. The core comprisesflaky particles, the D₅₀ particle diameter of the flaky particles in thecore is 5-10 μm, and the D₅₀ particle diameter of particles in the outerlayer is 0.1-4.5 μm, so that the rate capability of the lithium ionbattery prepared from the nickel cobalt lithium manganate cathodematerial is improved.

According to the nickel cobalt lithium manganate cathode material of thedisclosure, preferably, the core porosity is 8-15%, and the outer layerporosity is 20-40%. Namely, the nickel cobalt lithium manganate of thedisclosure has the compact inside and the loose and porous outside.

According to the nickel cobalt lithium manganate cathode material of thedisclosure, preferably, the D₅₀ particle diameter of the flaky particlesin the core is 7-10 μm, and the D₅₀ particle diameter of particles inthe outer layer is 0.9-2.5 μm, so that the rate capability of thelithium ion battery prepared from the nickel cobalt lithium manganatecathode material is obviously improved.

According to the nickel cobalt lithium manganate cathode material of thedisclosure, preferably, the chemical formula of the nickel cobaltlithium manganate is LiNi_(x)Co_(y)Mn_(1-x-y)O₂, wherein 0<x<1, 0<y<1,and 0<1-x-y<1, so that the rate capability of the lithium ion batteryprepared from the nickel cobalt lithium manganate cathode material isobviously improved.

According to the nickel cobalt lithium manganate cathode material of thedisclosure, preferably, the content of Ag in the cathode material islower than 20 ppm (preferably lower than 10 ppm), so that the influenceon the subsequent lithium ion battery performance by too high Ag contentcan be avoided.

The nickel cobalt lithium manganate cathode material of the disclosurehas the specific surface area being preferably 0.1-10 m²/g, morepreferably 0.5-1.5 m²/g, so that the rate capability of the finallyprepared lithium ion battery can be excellent.

The disclosure provides a method for preparing the cathode material in afifth aspect. The method comprises the step of calcining the lithiumsource with the nickel cobalt manganese hydroxide or the nickel cobaltmanganese hydroxide prepared by the above-mentioned method.

The method of the disclosure can further comprise the steps of uniformlymixing the lithium source with the prepared nickel cobalt manganesehydroxide and then performing calcination.

According to the method of the disclosure, the lithium source can bevarious lithium-containing compounds capable of being used for thelithium ion battery in the art, and for example, can be lithiumcarbonate and/or lithium hydroxide.

According to the method of the disclosure, preferably, the mol ratio ofthe element Li to the nickel cobalt manganese hydroxide is (1.0-1.1):1,more preferably (1.0-1.08):1, so that the chemical formula of theprepared nickel cobalt lithium manganate is LiNi_(x)Co_(y)Mn_(1-x-y)O₂,wherein 0<x<1, 0<y<1, and 0<1-x-y<1.

According to the method of the disclosure, the calcination conditionscan be various calcination conditions in the art, and for example, caninclude the temperature being 600-1100° C., preferably 750-950° C., andthe time being 8-20 h, preferably 10-15 h. In the disclosure, thecalcination oxidization environment can be provided by air and/or oxygengas, and for example, can be realized through introducing air and/oroxygen gas into the muffle furnace.

The disclosure provides a lithium ion battery in a sixth aspect. Thelithium ion battery comprises the cathode material or the cathodematerial prepared by the above-mentioned method.

The preparation method of the lithium ion battery of the disclosure canbe various conventional preparation methods of the lithium ion batteryin the art, and for example, can comprise the steps of: i. plugging twolayers of foamed nickel in an anode case, and putting the anode case anda cathode case into a baking oven to be baked for 30-40 min; ii.transferring a cathode plate (including the prepared cathode material)and the cathode case and the anode case taken out from the baking oveninto a glove box, and starting the assembly from an anode; iii. puttingthe anode case onto filter paper, taking out a lithium plate, puttingthe lithium plate onto the foamed nickel in the anode case, and flatlyclamping the lithium plate by a clamp; iv. putting the cathode case ontothe filter paper, putting in the pressed cathode plate, putting thecathode plate in the right center position of the cathode case, ensuringslight taking and slight putting during the putting-in to avoid materialfalling from the cathode plate, and infusing a proper amount ofelectrolyte, v. adding a layer of diaphragm paper, wherein during thediaphragm paper addition, one end of the diaphragm paper is firstlysoaked with the electrolyte, and then the other end is slowly put downso that the diaphragm paper is completely soaked with the electrolytewithout bubbles in the middle; vi. infusing a proper amount ofelectrolyte, covering the anode case, and after the flat putting,slightly exerting pressure to press down the anode case and to sleevethe anode case into the cathode case; and vii. taking out the battery,sealing the opening in a way of maintaining the constant pressure andstatic pressure of each battery to the greatest extent, and cleanlywiping the electrolyte on the surface of the battery after the openingsealing.

The energy density of the lithium ion battery of the disclosure is ashigh as 1.5-2.5 Wh/cm³, and the rate capability 5 C/0.2 C is as high as90-99%.

The disclosure will be illustrated in detail hereafter throughembodiments.

The SEM is an S4800 scanning electron microscope produced by Hitachi(Japanese company), and has the test voltage of 5 KV.

A preparation method of the lithium ion battery comprises the steps of:i. plugging two layers of foamed nickel in the anode case, and puttingthe anode case and the cathode case into the baking oven to be baked for30 min; ii. transferring the cathode plate (including the preparedcathode material) and the cathode case and the anode case taken out fromthe baking oven into the glove box, and starting the assembly from theanode; iii. putting the anode case onto the filter paper, taking out thelithium plate, putting the lithium plate onto the foamed nickel in theanode case, and flatly clamping the lithium plate by the clamp; iv.putting the cathode case onto the filter paper, putting in the pressedcathode plate, putting the cathode plate in the right center position ofthe cathode case, ensuring slight taking and slight putting during theputting-in to avoid material falling from the cathode plate, andinfusing a proper amount of electrolyte; v. adding one layer of Φ16diaphragm paper, wherein during the diaphragm paper addition, one end ofthe diaphragm paper is firstly soaked with the electrolyte, and then theother end is slowly put down so that the diaphragm paper is completelysoaked with the electrolyte without bubbles in the middle; vi. infusinga proper amount of electrolyte, covering the anode case, and after theflat putting, slightly exerting pressure to press down the anode caseand to sleeve the anode case into the cathode case; and vii. taking outthe battery, sealing the opening in a way of maintaining the constantpressure and static pressure of each battery to the greatest extent, andcleanly wiping the electrolyte on the surface of the battery after theopening sealing.

The disclosure will be further illustrated hereafter throughembodiments, but is not limited thereto.

Embodiment 1

The embodiment is used for illustrating the nickel cobalt manganesehydroxide, the cathode material, the preparation method thereof and thelithium ion battery of the disclosure.

(1) 7.495 kg of CoSO₄·7H₂O, 7.009 kg of NiSO₄·6H₂O and 4.507 kg ofMnSO₄·H₂O are dissolved into deionized water to be prepared into 40 L of2.0 molL⁻¹ nickel, cobalt and manganese sulfate solution; 6.4 kg of NaOHis dissolved into the deionized water to be prepared into 40 L of 4.0molL⁻¹ sodium hydroxide solution; 1.632 kg of ammonium hydroxide withthe mass percentage being 25% is dissolved into the deionized water tobe prepared into 40 L of 0.6 molL⁻¹ ammonium hydroxide solution; astirring paddle is started at the speed of 5 ms⁻¹; then the nickel,cobalt and manganese sulfate solution, the sodium hydroxide solution andthe ammonium hydroxide solution are simultaneously dripped into areaction kettle (at the dripping speed of 0.2 L/h) in nitrogen gasatmosphere to take a complex-precipitation reaction; the reaction iscontinuously performed for 40 h; then a Pt electrode is inserted intothe reaction kettle to form an electrolytic tank with stainless steel ofthe reaction kettle; 0.3 g of Ag powder is added into the reactionkettle; a 32 V pulse power supply is switched on; the pulse ratio is1:1; the pulse current coprecipitation reaction is continuouslyperformed for 30 h; prepared slurry is washed for 5 times; drying isperformed at 100° C.; and nickel cobalt manganese hydroxide powder A1with a core and an outer layer covering the outside of the core isobtained. The chemical formula of the nickel cobalt manganese hydroxidepowder A1 is Ni_(1/3)Co_(1/3)Mn_(1/3)(OH)₂. FIG. 1 is an SEM pattern(30000 times) of the nickel cobalt manganese hydroxide powder A1. FIG. 2is an SEM pattern (1000 times) of the nickel cobalt manganese hydroxidepowder A1.

(2) 0.37 kg of lithium carbonate and 0.915 kg of nickel cobalt manganesehydroxide powder prepared in the step (1) are weighed and taken, anduniformly mixed by a high-speed material mixing machine according to amol ratio of the lithium source (metered by the element Li) and thenickel cobalt manganese hydroxide powder being 1:1. The air isintroduced into a muffle furnace to heat the material to 950° C.Constant temperature sintering is performed for 12 h, then the materialis cooled to the room temperature, a nickel cobalt lithium manganatefinished product material B1 with a core and an outer layer covering theoutside of the core is obtained, and the chemical formula isLiNi_(1/3)Co_(1/3)Mn_(1/3)O₂.

(3) The nickel cobalt lithium manganate finished product material B1prepared in the step (2) is used for preparing a lithium ion battery C1.

Embodiment 2

The embodiment is used for illustrating the nickel cobalt manganesehydroxide, the cathode material, the preparation method thereof and thelithium ion battery of the disclosure.

(1) 7.495 kg of CoSO₄·7H₂O, 7.009 kg of NiSO₄·6H₂O and 4.507 kg ofMnSO₄·H₂O are dissolved into deionized water to be prepared into 40 L of2.0 molL⁻¹ nickel, cobalt and manganese sulfate solution; 16 kg of NaOHis dissolved into deionized water to be prepared into 40 L of 10 molL⁻¹sodium hydroxide solution; 3.264 kg of ammonium hydroxide with the masspercentage being 25% is dissolved into the deionized water to beprepared into 40 L of 1.2 molL⁻¹ ammonium hydroxide solution; thestirring paddle is started at the speed of 4 ms⁻¹; then the nickel,cobalt and manganese sulfate solution, the sodium hydroxide solution andthe ammonium hydroxide solution are simultaneously dripped into areaction kettle (at the dripping speed of 2 L/h) in nitrogen gasatmosphere to take a complex-precipitation reaction; the reaction iscontinuously performed for 40 h; then a Pt electrode is inserted intothe reaction kettle to form an electrolytic tank with stainless steel ofthe reaction kettle; 0.5 g of Ag powder is added into the reactionkettle; a 32 V pulse power supply is switched on; the pulse ratio is1:3; the pulse current coprecipitation reaction is continuouslyperformed for 5 h; prepared slurry is washed for 5 times; drying isperformed at 110° C.; and nickel cobalt manganese hydroxide powder A2with a core and an outer layer covering the outside of the core isobtained. The chemical formula of the nickel cobalt manganese hydroxidepowder A2 is Ni_(1/3)Co_(1/3)Mn_(1/3)(OH)₂.

(2) 0.37 kg of lithium carbonate and 0.915 kg of nickel cobalt manganesehydroxide powder prepared in the step (1) are weighed and taken, anduniformly mixed by a high-speed material mixing machine according to amol ratio of the lithium source (metered by the element Li) and thenickel cobalt manganese hydroxide powder being 1:1. The air isintroduced into the muffle furnace to heat the material to 750° C.Constant temperature sintering is performed for 20 h, then the materialis cooled to the room temperature, a nickel cobalt lithium manganatefinished product material B2 with a core and an outer layer covering theoutside of the core is obtained, and the chemical formula isLiNi_(1/3)Co_(1/3)Mn_(1/3)O₂.

(3) The nickel cobalt lithium manganate finished product material B2prepared in the step (2) is used for preparing a lithium ion battery C2.

Embodiment 3

The embodiment is used for illustrating the nickel cobalt manganesehydroxide, the cathode material, the preparation method thereof and thelithium ion battery of the disclosure.

(1) 7.495 kg of CoSO₄·7H₂O, 7.009 kg of NiSO₄·6H₂O and 4.507 kg ofMnSO₄·H₂O are dissolved into deionized water to be prepared into 40 L of2.0 molL⁻¹ nickel, cobalt and manganese sulfate solution; 6.4 kg of NaOHis dissolved into deionized water to be prepared into 40 L of 4.0 molL⁻¹sodium hydroxide solution; 1.632 kg of ammonium hydroxide with the masspercentage being 25% is dissolved into the deionized water to beprepared into 40 L of 0.6 molL⁻¹ ammonium hydroxide solution; thestirring paddle is started at the speed of 3 ms⁻¹; then the nickel,cobalt and manganese sulfate solution, the sodium hydroxide solution andthe ammonium hydroxide solution are simultaneously dripped into areaction kettle (at the dripping speed of 1 L/h) in nitrogen gasatmosphere to take a complex-precipitation reaction; the reaction iscontinuously performed for 40 h; then a Pt electrode is inserted intothe reaction kettle to form an electrolytic tank with stainless steel ofthe reaction kettle; 0.6 g of Ag powder is added into the reactionkettle; a 32 V pulse power supply is switched on; the pulse ratio is1:5; the pulse current coprecipitation reaction is continuouslyperformed for 1 h; prepared slurry is washed for 5 times; drying isperformed at 120° C.; and nickel cobalt manganese hydroxide powder A3with a core and an outer layer covering the outside of the core isobtained. The chemical formula of the nickel cobalt manganese hydroxidepowder A3 is Ni_(1/3)Co_(1/3)Mn_(1/3)(OH)₂.

(2) 0.37 kg of lithium carbonate and 0.915 kg of nickel cobalt manganesehydroxide powder prepared in the step (1) are weighed and taken, anduniformly mixed by a high-speed material mixing machine according to amol ratio of the lithium source (metered by the element Li) and thenickel cobalt manganese hydroxide powder being 1:1. The air isintroduced into the muffle furnace to heat the material to 800° C.Constant temperature sintering is performed for 20 h, then the materialis cooled to the room temperature, a nickel cobalt lithium manganatefinished product material B3 with a core and an outer layer covering theoutside of the core is obtained, and the chemical formula isLiNi_(1/3)Co_(1/3)Mn_(1/3)O₂.

(3) The nickel cobalt lithium manganate finished product material B3prepared in the step (2) is used for preparing a lithium ion battery C3.

Embodiment 4

The embodiment is used for illustrating the nickel cobalt manganesehydroxide, the cathode material, the preparation method thereof and thelithium ion battery of the disclosure.

(1) 7.495 kg of CoSO₄·7H₂O, 7.009 kg of NiSO₄·6H₂O and 4.507 kg ofMnSO₄·H₂O are dissolved into deionized water to be prepared into 40 L of2.0 molL⁻¹ nickel, cobalt and manganese sulfate solution; 8.98 kg of KOHis dissolved into the deionized water to be prepared into 40 L of 4.0molL⁻¹ potassium hydroxide solution; 1.632 kg of ammonium hydroxide withthe mass percentage being 25% is dissolved into the deionized water tobe prepared into 40 L of 0.6 molL⁻¹ ammonium hydroxide solution; thestirring paddle is started at the speed of 3 ms⁻¹; then the nickel,cobalt and manganese sulfate solution, the potassium hydroxide solutionand the ammonium hydroxide solution are simultaneously dripped into areaction kettle (at the dripping speed of 0.2 L/h) in nitrogen gasatmosphere to take a complex-precipitation reaction; the reaction iscontinuously performed for 40 h; then a Pt electrode is inserted intothe reaction kettle to form an electrolytic tank with stainless steel ofthe reaction kettle; 0.3 g of Ag powder is added into the reactionkettle; a 32 V pulse power supply is switched on; the pulse ratio is1:1; the pulse current coprecipitation reaction is continuouslyperformed for 15 h; prepared slurry is washed for 5 times; drying isperformed at 100° C.; and nickel cobalt manganese hydroxide powder A4with a core and an outer layer covering the outside of the core isobtained. The chemical formula of the nickel cobalt manganese hydroxidepowder A4 is Ni_(1/3)Co_(1/3)Mn_(1/3)(OH)₂.

(2) 0.026 kg of lithium carbonate and 0.915 kg of nickel cobaltmanganese hydroxide powder prepared in the step (1) are weighed antaken, and uniformly mixed by a high-speed material mixing machineaccording to a mol ratio of the lithium source (metered by the elementLi) and the nickel cobalt manganese hydroxide powder being 1.08:1. Theair is introduced into the muffle furnace to heat the material to 950°C. Constant temperature sintering is performed for 12 h, then thematerial is cooled to the room temperature, a nickel cobalt lithiummanganate finished product material B4 with a core and an outer layercovering the outside of the core is obtained, and the chemical formulais LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂.

(3) The nickel cobalt lithium manganate finished product material B4prepared in the step (2) is used for preparing a lithium ion battery C4.

Embodiment 5

The embodiment is used for illustrating the nickel cobalt manganesehydroxide, the cathode material, the preparation method thereof and thelithium ion battery of the disclosure.

A nickel cobalt manganese hydroxide A5, a cathode material B5 and alithium ion battery C5 are prepared by the method according to theembodiment 1. The difference is that relative to 1566.0 g of element Ni,the consumption of Ag powder is 1.0 g.

Embodiment 6

The embodiment is used for illustrating the nickel cobalt manganesehydroxide, the cathode material, the preparation method thereof and thelithium ion battery of the disclosure.

A nickel cobalt manganese hydroxide A6, a cathode material B6 and alithium ion battery C6 are prepared by the method according to theembodiment 1. The difference is that relative to 1566.0 g of element Ni,the consumption of Ag powder is 0.8 g.

Embodiment 7

The embodiment is used for illustrating the nickel cobalt manganesehydroxide, the cathode material, the preparation method thereof and thelithium ion battery of the disclosure.

A nickel cobalt manganese hydroxide A7, a cathode material B7 and alithium ion battery C7 are prepared by the method according to theembodiment 1. The difference is that the pulse ratio of the pulsecurrent coprecipitation reaction is 6:1, and the reaction time is 10 h.

Embodiment 8

The embodiment is used for illustrating the nickel cobalt manganesehydroxide, the cathode material, the preparation method thereof and thelithium ion battery of the disclosure.

A nickel cobalt manganese hydroxide A8, a cathode material B8 and alithium ion battery C8 are prepared by the method according to theembodiment 1. The difference is that the pulse ratio of the pulsecurrent coprecipitation reaction is 1:20, and the reaction time is 10 h.

Embodiment 9

The embodiment is used for illustrating the nickel cobalt manganesehydroxide, the cathode material, the preparation method thereof and thelithium ion battery of the disclosure.

A nickel cobalt manganese hydroxide A10, a cathode material B10 and alithium ion battery C10 are prepared by the method according to theembodiment 1. The difference is that the temperature of thecomplex-precipitation reaction is 90° C., and the time is 40 h.

Contrast Embodiment 1

A nickel cobalt manganese hydroxide D1, a cathode material DS1 and alithium ion battery DSS1 are prepared by the method according toembodiment 1. The difference is that the nickel cobalt manganesehydroxide obtained through the complex-precipitation reaction isdirectly washed and dried, pulse current coprecipitation reaction is notperformed, FIG. 3 is an SEM pattern (20000 times) of nickel cobaltmanganese hydroxide D1 powder, and FIG. 4 is an SEM pattern (1000 times)of the nickel cobalt manganese hydroxide D1 powder.

Test Embodiment

1. The nickel cobalt manganese hydroxide powder A1-A9 and D1 and nickelcobalt lithium manganate cathode materials B1-B9 and DS1 are observed bythe SEM to obtain the SEM pattern. Then through SEM software, theparticle diameter distribution of the flaky particles in the core of thenickel cobalt manganese hydroxide powder and the particle diameterdistribution of the particles in the outer layer are obtained (testmethod: the powder is subjected to ion grinding by an ion grindinginstrument to obtain powder cross section. Then the SEM is used forobserving the powder cross section to obtain the cross section SEMpattern, the cross section SEM pattern is measured, the diameter averagevalue of a core flaky particle region, i.e., the D₅₀ of the flakyparticles of the core is counted and measured, and the thickness averagevalue of an outer layer particle region, i.e., the D₅₀ of the particlesof the outer layer is counted and measured). The specific results areshown in Table 1.

2. The porosities of the core and the outer layer of the nickel cobaltmanganese hydroxide powder A1-A9 and D1 and the nickel cobalt lithiummanganate cathode materials B1-B9 and DS1 are measured (test method: thepowder is subjected to ion grounding by the ion grinding instrument toobtain powder cross section. Then the SEM is used for observing thepowder cross section to obtain the cross section SEM pattern, the crosssection SEM pattern is measured, the ratio of pore area of the coreflaky particle region/the total area of the core, i.e. the core porosityis counted and measured, and the ratio of the pore area of the outerlayer particle region/the total area of the outer layer, i.e. the outerlayer porosity is counted and measured). The specific results are shownin Table 1.

3. The Ag content of the nickel cobalt manganese hydroxide powder A1-A9and D1 and the nickel cobalt lithium manganate cathode materials B1-B9and DS1 is measured by an inductively coupled plasma spectrometer, andthe measured results are shown in Table 1.

4. The specific surface area of the nickel cobalt manganese hydroxidepowder A1-A9 and D1 and the nickel cobalt lithium manganate cathodematerials B1-B9 and DS1 is measured by using a specific surface areatest instrument, and the measured results are shown in Table 1.

5. The battery energy density of the lithium ion batteries C1-C9 andDSS1 is calculated according to a following formula 1, the ratecapability 5 C/0.2 C of the lithium ion batteries C1-C9 and DSS1 iscalculated according to a following formula 2, and the measured resultsare shown in Table 2.

Formula 1: battery energy density=UIt/g*powder compression density(wherein the U is the material charging average voltage, the I ischarging and discharging current, the t is the charging and dischargingtime, and the unit of the powder compaction density is g/cm³), and theunit of the battery energy density is Wh/cm³.

Formula 2: battery rate capability 5 C/0.2 C=5*material ratedcapacity/0.2*material rated capacity (wherein the material ratedcapacity refers to the theoretical capacity of the material per se).

TABLE 1 Nickel cobalt manganese hydroxide Nickel cobalt lithiummanganate D₅₀ particle D₅₀ particle Outer D₅₀ particle D₅₀ particlediameter of Core diameter of layer Specific diameter of Core diameter ofOuter Specific core flaky poro- outer layer poro- surface Ag core flakyporo- outer layer layer surface Ag Serial particles sity particles sityarea content particles sity particles porosity area content number (μm)(%) (μm) (%) (m²/g) (ppm) (μm) (%) (μm) (%) (m²/g) (ppm) Embodiment 7.135 0.5 58 6.5 2.5 8.0 10 1.4 28 0.8 2.4 1 Embodiment 7.0 34 0.5 52 6.35.1 7.7  8 1.4 22 0.6 4.7 2 Embodiment 7.2 36 0.9 57 6.6 7.7 8.1 11 1.829 0.9 7.2 3 Embodiment 7.0 35 1.4 53 6.5 2.6 8.2 10 2.4 23 0.7 2.5 4Embodiment 7.1 38 0.6 55 6.5 8.5 8.0 12 1.6 26 0.8 8.5 5 Embodiment 7.140 0.6 55 6.5 8 8.0 14 1.5 26 0.8 8 6 Embodiment 7.1 36 1.26 54 5.3 2.58.0 12 2.21 20 0.5 2.4 7 Embodiment 7.1 38 0.1 54 7.5 2.5 8.0 15 0.9 351.3 2.4 8 Embodiment 9 51 0.5 55 6.5 2.5 10.1 13 1.4 26 0.8 2.4 9Contrast 4.8 25 — — 5.0 0 8.0 10 — — 0.4 0 embodiment 1

TABLE 2 Battery energy density Battery rate capability Serial number(Wh/cm³) 5C/0.2C (%) Embodiment 1 2.40 98.3 Embodiment 2 2.41 98.5Embodiment 3 2.39 98.7 Embodiment 4 2.37 98.6 Embodiment 5 2.03 97.7Embodiment 6 2.23 97.9 Embodiment 7 2.32 90.6 Embodiment 8 2.01 97.5Embodiment 9 1.83 98.6 Contrast embodiment 1 1.42 81.2

Through the results in Table 1, it is observed that the nickel cobaltmanganese hydroxide prepared by the method of the disclosure has a coreand an outer layer covering the outside of the core. The core is flakyparticles, the core porosity is 30-51%, the D₅₀ particle diameter of theflaky particles in the core is 5-8 the outer layer porosity is 52-60%,the D₅₀ particle diameter of particles in the outer layer is 0.1-5 andthe specific surface area is 5.0-8.0 m²/g. The prepared nickel cobaltlithium manganate also has a core and an outer layer covering theoutside of the core, the core is flaky particles, the core porosity is8-15%, the D₅₀ particle diameter of the flaky particles in the core is7-10 the outer layer porosity is 20-40%, the D₅₀ particle diameter ofparticles in the outer layer is 0.9-2.5 and the specific surface area is0.5-1.5 m²/g. Therefore the energy density of the lithium ion batteryprepared from the nickel cobalt lithium manganate of the disclosure isas high as 1.5-2.5 Wh/cm³, and the rate capability 5 C/0.2 C is as highas 90-99%. Specifically, a layer of loose and porous nickel cobaltmanganese hydroxide particles is formed on the surface of the originalcompact nickel cobalt manganese hydroxide particles in a pulse currentprecipitation mode. The inside particles of the nickel cobalt manganesehydroxide prepared by the method are compact, the outside is loose andporous, the tap density is high, and the crystallinity degree is high.Further, the nickel cobalt lithium manganate finished product materialprepared from the nickel cobalt manganese hydroxide also has a structurewith the high-compactness inside and loose and porous outside, and hasexcellent crystallinity degree and conductivity. The battery preparedfrom the prepared nickel cobalt lithium manganate finished productmaterial has high energy density and good rate capability.

The preferred embodiments of the present disclosure are described indetail above, but the present disclosure is not limited to the specificdetails in the above embodiments. Various simple variations may be madeto the technical solutions of the present disclosure within the scope ofthe technical idea of the present disclosure, and such simple variationsshall all fall within the protection scope of the present disclosure.

It should be further noted that the specific technical featuresdescribed in the above specific embodiments may be combined in anysuitable manner without contradiction. To avoid unnecessary repetition,various possible combinations are not further described in the presentdisclosure.

In addition, the various embodiments of the present disclosure may becombined without departing from the idea of the present disclosure, andsuch combinations shall also fall within the scope of the presentdisclosure.

In the descriptions of this specification, descriptions using referenceterms “an embodiment”, “some embodiments”, “an example”, “a specificexample”, or “some examples” mean that specific characteristics,structures, materials, or features described with reference to theembodiment or example are included in at least one embodiment or exampleof the present disclosure. In this specification, schematic descriptionsof the foregoing terms do not necessarily directed at a same embodimentor example. In addition, the described specific features, structures,materials, or features can be combined in a proper manner in any one ormore embodiments or examples. In addition, in a case that is notmutually contradictory, a person skilled in the art can combine or groupdifferent embodiments or examples that are described in thisspecification and features of the different embodiments or examples.

Although the embodiments of the present disclosure are shown anddescribed above, it can be understood that, the foregoing embodimentsare exemplary, and cannot be construed as a limitation to the presentdisclosure. Within the scope of the present disclosure, a person ofordinary skill in the art may make changes, modifications, replacement,and variations to the foregoing embodiments.

What is claimed is:
 1. A nickel cobalt lithium manganate cathodematerial, comprising: a nickel cobalt lithium manganate, wherein thenickel cobalt lithium manganate in the nickel cobalt lithium manganatecathode material comprises: a core and an outer layer covering theoutside of the core, the core comprises flaky particles, a D50 particlediameter of the flaky particles in the core is 5-10 μm, and a D50particle diameter of particles in the outer layer is 0.1-4.5 μm.
 2. Thenickel cobalt lithium manganate cathode material according to claim 1,wherein a porosity of the core is 8-15%, and a porosity of the outerlayer is 20-40%.
 3. The nickel cobalt lithium manganate cathode materialaccording to claim 1, wherein the D₅₀ particle diameter of the flakyparticles in the core is 7-10 μm, and the D₅₀ particle diameter ofparticles in the outer layer is 0.9-2.5 μm.
 4. The nickel cobalt lithiummanganate cathode material according to claim 1, wherein a content of Agin the cathode material is lower than 20 ppm.
 5. The nickel cobaltlithium manganate cathode material according to claim 1, wherein aspecific surface area of the cathode material is 0.1-10 m²/g.
 6. Thenickel cobalt lithium manganate cathode material according to claim 1,wherein a specific surface area of the cathode material is 0.5-1.5 m²/g.7. The nickel cobalt lithium manganate cathode material according toclaim 1, wherein a chemical formula of the nickel cobalt lithiummanganate is LiNi_(x)Co_(y)Mn_(1-x-y)O₂, wherein 0<x<1, 1, and0<1-x-y<1.
 8. The nickel cobalt lithium manganate cathode materialaccording to claim 1, wherein the particles of the outer layer aresmaller than the flaky particles in the core, and the particles of theouter layer are attached onto surfaces of the flaky particles in thecore with gaps such that the outer layer is porous.
 9. A method forpreparing the nickel cobalt lithium manganate cathode material accordingto claim 1, comprising the step of calcining a lithium source and anickel cobalt manganese hydroxide, wherein the nickel cobalt manganesehydroxide comprises a core and an outer layer covering an outside of thecore, and the core comprises flaky particles, a D₅₀ particle diameter offlaky particles in the core is 5-8 μm, and a D₅₀ particle diameter ofparticles in the outer layer is 0.1-5 μm.
 10. The method according toclaim 9, wherein a mol ratio of the element Li in the lithium source tothe nickel cobalt manganese hydroxide is (1.0-1.1):1.
 11. The methodaccording to claim 9, wherein a mol ratio of the element Li in thelithium source to the nickel cobalt manganese hydroxide is (1.0-1.08):1.12. The method according to claim 9, wherein a temperature of thecalcination is 600-1100° C., and a time of the calcination is 8-20 h.13. The method according to claim 9, wherein a temperature of thecalcination is 750-950° C., and a time of the calcination is 10-15 h.14. The method according to claim 9, wherein a chemical formula of thenickel cobalt manganese hydroxide is Ni_(x)Co_(y)Mn_(1-x-y)(OH)₂,wherein 0<x<1, 0<y<1, and 0<1-x-y<1.
 15. The method according to claim9, wherein a porosity of the core is 30-51%, and a porosity of the outerlayer is 52-60%.
 16. The method according to claim 9, wherein a D₅₀particle diameter of the flaky particles in the core is 5-7.5 μm, and aD₅₀ particle diameter of particles in the outer layer is 0.1-4.5 m. 17.The method according to claim 9, wherein the nickel cobalt manganesehydroxide comprises Ag, a content of the Ag is lower than 20 ppm. 18.The method according to claim 9, wherein a specific surface area of thenickel cobalt manganese hydroxide is 0.1-10 m²/g.
 19. The methodaccording to claim 9, wherein a specific surface area of the nickelcobalt manganese hydroxide is 5-8 m²/g.
 20. A lithium ion battery,comprising the nickel cobalt lithium manganate cathode materialaccording to claim 1.